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Biomedical subjects

B London

Publications and source records attributed to B London.

31 records · Page 2Linked to original sources
PubMed1993

The political and economic determinants of health outcomes: a cross-national analysis.

This article investigates the impact of selected political and economic processes on the well-being of domestic populations within samples of 50 to 84 peripheral and noncore nations. Existing research by Cereseto and Waitzkin on the relative merits of market versus socialist systems for the provision of health and welfare needs of their populations is extended by employing a more complex model than the original study. More specifically, the authors assess the impact on measures of population health and mortality rates of regime ideology, state strength, multinational corporate penetration, and position in the world economy. In general, high levels of democracy and strong left-wing regimes are associated with positive health outcomes, and strong right-wing regimes have populations with lower life expectancies and higher levels of various measures of mortality. These findings support the conclusion that political systems make a difference in health and well-being independent of national (gross national product per capita) and international (investment dependency) economic factors.

Adolescent↗
PubMed1992

A lineage-specific t(1;14)(q21;q32) as an early event in development of B-cell clonal expansion.

We report a patient in whom a cell line of 47,XY,+X,t(1;14)(q21;q32) constitution was found in a lymph node excised from the neck. Histologic examination and immunophenotyping both in situ and by flow cytometry failed to confirm a diagnosis of B-cell lymphoma, but Southern analysis indicated the presence of B-cell clonal expansion. These observations support the concept that primary chromosomal abnormalities occur in clonal expansions in the very earliest stages of tumorigenesis.

B-Lymphocytes↗
PubMed1990

Convergence in world urbanization? A quantitative assessment.

"Cross-national data are used to explore the question of whether world urban patterns and processes are converging or diverging. We compare tabular data on overall percent urban, urban primacy, overurbanization, and urban bias across world-system strata and global regions. The evidence suggests continuing differences and little evidence for convergence. To determine whether world-system effects have causal efficacy, we conclude with a regression analysis. These results provide strong evidence for a world-system explanation of continuing differences in overall level of urbanization and urban primacy, and a developmentalist approach seems to explain persisting divergence in levels of urban bias."

Demography↗
PubMed1986

Contraction in voltage-clamped, internally perfused single heart cells.

We studied contraction in single voltage-clamped, internally perfused myocytes isolated from guinea pig ventricles. The microscopic appearance of the cell was observed and recorded with a television system, while contractile shortening was measured 1,000 times/s using a linear photodiode array. Uniform, synchronous sarcomere shortening occurred in response to depolarizations that triggered a slow inward current (Isi). Changes in Isi caused by altering the amplitude of the voltage step, the extracellular [Ca2+], or the holding potential were accompanied by immediate parallel changes in the extent and velocity of shortening. In particular, twitch shortening during depolarization was immediately decreased when large voltage steps decreased Isi, and was eliminated by depolarizations that exceeded +75 mV, the apparent reversal potential for Ca2+. In these cases, shortening was associated with the tail current during repolarization. Increases in the amplitude, duration, and the rate of the depolarizing step increased the extent and speed of sarcomere shortening over the course of four to five contractions without a simultaneous parallel increase of Isi. Large prolonged depolarizations caused an asynchronous, nonuniform, oscillatory shortening of the cell and potentiated future twitch contractions. Increases in the duration of the depolarizing step immediately prolonged contraction; otherwise, interventions that altered the extent, velocity, and time course of shortening in intact, nonperfused cells did not affect the time course of the contraction in the internally perfused single cells. Our results provide direct support for the hypothesis that Isi both induces and grades the size of the Ca2+ release from the sarcoplasmic reticulum of intact cardiac muscle. In addition, a separate, depolarization-dependent process unrelated to Isi grades the size of contraction, presumably by modulating Ca2+ accumulation in the intracellular stores, and affects its time course.

Animals↗
PubMed1985

Low dose cytosine arabinoside in acute myeloid leukemia: remission is not due to differentiation induction.

A patient with acute nonlymphoblastic leukemia (FAB M4), showing a near tetraploid chromosome complement on his marrow cells, was treated with low dose cytosine arabinoside and achieved remission. During remission the near tetraploid marrow chromosome complement disappeared and reappeared upon relapse of leukemia. These findings are interpreted as evidence against differentiation induction in the leukemic cell line as a mechanism for remission of the disease in this patient.

Aged↗
PubMed1984

Contraction bands: differences between physiologically vs. maximally activated single heart muscle cells.

High resolution interference and phase microscopy were used to inspect the striations' appearance in shortening rat heart cells. Isolated cells were treated with detergent so that shortening could be graded by addition of calcium. Upon activation sarcomeres shortened to form (a) contraction densities in the middle of the A band at 1.7 micrometer (b) disappearance of the I bands and (c) phase brightening of the A bands at 1.6 micrometer and (d) dense Cz contraction bands at shorter lengths. These changes are totally consistent with the uniform sliding of myofilaments of previously accepted fixed dimensions. However, the striated patterns differed significantly in intact cells which were electrically stimulated to shorten. Here individual A bands remained distinct, without phase brightening or contraction band formation despite sarcomere shortening to less than the length of the A band as measured in the unstimulated cell. Maximal activation of intact cells by barium contracture elicited the full sequence of striation changes (a-d) seen in the chemically skinned cells. Light diffraction analysis gave comparable interpretation, i.e., the protein within the shortened sarcomere in the physiologically activated cardiac cell is more narrowly distributed than expected for thick filaments of fixed dimensions. These optical differences may reflect the restricted presence of the globular myosin heads at the ends of the cardiac sarcomere. This situation would explain the narrow range of the cardiac length-tension relation.

Animals↗
PubMedDate not supplied

Cardiovascular tissues contain independent circadian clocks.

Acute cardiovascular events exhibit a circadian rhythm in the frequency of occurrence. The mechanisms underlying these phenomena are not yet fully understood, but they may be due to rhythmicity inherent in the cardiovascular system. We have begun to characterize rhythmicity of the clock gene mPer1 in the rat cardiovascular system. Luciferase activity driven by the mPer1 gene promoter is rhythmic in vitro in heart tissue explants and a wide variety of veins and arteries cultured from the transgenic Per1-luc rat. The tissues showed between 3 and 12 circadian cycles of gene expression in vitro before damping. Whereas peak per1-driven bioluminescence consistently occurred during the late night in the heart and all arteries sampled, the phases of the rhythms in veins varied significantly by anatomical location. Varying the time of the culture procedure relative to the donor animal's light:dark cycle revealed that, unlike some other rat tissues such as liver, the phases of in vitro rhythms of arteries, veins, and heart explants were affected by culture time. However, phase relationships among tissues were consistent across culture times; this suggests diversity in circadian regulation among components of the cardiovascular system.

Animals↗